Follow these steps to color points, lines, and triangles using attributes:
Select your design in the object list and enter edit mode in the design.
Expand the ATTRIBUTE section in the right panel for the design.
Check the Color Coding checkbox to enable color coding via attributes for your design and check that Color is selected.
Click Set Attributes on objects button.
Add the standard attribute Color via click on the + icon.
Choose a color that you want to apply to objects in your design.
If you want to add the color on new objects in your design just click on the play icon.
If you want to add the color on existing object. Use the Selection tool or the Ctrl shortcut to select points, lines, or triangles that you want to color. Then click on the Update Marked Objects icon in the toolbar to add the color attribute to the selected objects.